RFR(XXS): 8227338: templateInterpreter.cpp: copy_table() needs to be safer

[Daniel D. Daugherty]

Greetings,

During the code review for the following fix:

     JDK-8227117 normal interpreter table is not restored after single 
stepping with TLH
     https://bugs.openjdk.java.net/browse/JDK-8227117

Erik O. noticed a potential race with templateInterpreter.cpp: copy_table()
depending on C++ compiler optimizations. The following bug is being used
to fix this issue:

     JDK-8227338 templateInterpreter.cpp: copy_table() needs to be safer
     https://bugs.openjdk.java.net/browse/JDK-8227338

Here's the webrev URL:

     http://cr.openjdk.java.net/~dcubed/8227338-webrev/0_for_jdk14/

This fix has been tested via Mach5 Tier[1-3] on Oracle's usual platforms.
Mach5 tier[4-6] is running now. It has also been tested with the manual
jdb test from JDK-8227117 using 'release' and 'fastdebug' bits.

Thanks, in advance, for questions, comments or suggestions.

Dan